/******************************************************************************

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*******************************************************************************/
#include <stdio.h>

int
main ()
{
  int sum = 0, num;
  printf ("Enter a sum number:");
  scanf ("%d", &num);
  for (int n = 1; n <= num; n++)
	{
	  sum += n;
	}
  printf ("Hello World! sum = %d ", sum);

  return 0;
}